How do the four spark plugs look?

Did you jump the service connector when you checked the ignition timing?

If the small cracks in the exhaust manifold allow any outside air to enter into the exhaust, the engine will run rich.

You might want to measure the fuel pressure and check whether the fuel pressure regulator is working. Also check whether one of the fuel injectors is stuck open.

If you hear any valve tapping, you might want to check the valve clearances.

Are you experiencing low engine power?

 

I just swapped in new spark plugs this last week. The old ones looked fine, but after seafoaming the car I went and replaced them anyways.

As far as timing, I couldn't tell you. My buddy did it for me as he know 50000x more about cars then I ever will and is certified. Pretty confident he knew what he was doing.

As for the manifold cracks, They are so faint, I have a hard time believing that they are allowing are into them. If they are, it can't be much at all.

I will check fuel pressure and injection as the next step. Thank you for bringing that up. The valves could probably use to be adjusted as well. As far as low engine power, I'm not sure. I'm used to a heavily modified V8 so I'm not really certain what low engine power would entitle on this Civic. It does feel a little "weak" but it could just be me.

 

So I figure I'll give a little update. Got all the MPG's back, if not MORE. Pretty happy about that. I never got around to checking out the last post from RonJ. I'm getting about 33ish mpg right now, which in my book is pretty damn good. Beats the 13mpgs I'm getting in my truck....haha. Thanks for all of your help, I really appreciate it

 

So did you ever determine what the problem was? Just needed a tune up?

 

Not really. I should have done it in steps, to really see what was wrong, but I'm impatient and wanted to have it fixed since my other rig is down right now. All I did to it was clean the cap/rotor assm., spark plugs, seafoam, oil change, timing, and I think that's it. It still needs some work on the valves, but I'll get to that eventually. I'm pretty happy its back to the "old" mileage right now.